The present invention relates to hydraulic valve apparatus for providing a modular valve system between a directional valve and a standard subplate for controlling operation of conventional hydraulic devices, such as hydraulic cylinders and the like.
It is now conventional practice to provide directional valves and subplates which have standard arrangements of ports for directing flow of hydraulic fluid from and to pump and tank and between opposite ends of hydraulic cylinders. It is also known to provide a valve module which includes a manifold block that is sandwich-mounted between the directional valve and the subplate with ports and associated through passageways corresponding to the standard port arrangement, and in which a valve is mounted to perform a function on the hydraulic fluid flowing in a through passageway between associated ports of the directional valve and the subplate. In the known valve modules the valves are mounted on one of the sides of the manifold block and extend inward to a location wherein one or more transverse passageways as well as necessary pilot passageways can be located to provide required communication with the main or through passageways of the manifold block and to provide pilot control of the valve. In the prior art modules, it is the general rule that only one function can be performed by the module because the arrangements required for the transverse and pilot passageways for each included valve are sufficiently complex so as to preclude use of more than one type of flow-function valve within the boundaries of a manifold block. Thus, when a plurality of functions are to be performed within a valve system, a corresponding number of valve modules must be mounted together, thereby multiplying cost and space requirements accordingly.